Plants Flashcards
How are plants classified?
They are classified in the kingdom Plantae including non vascular(Bryophytes) and seedless vascular(pteridophytes) which includes cone bearing seed plants(gymnosperms) and flower bearing seed plants(angiosperms)
As well as green algae( managed to colonise land)
Briefly explain the anatomy of a flower
Flower also know as bloom or blossom is the fruit bearing part of the plant, consisting of reproductive organs(stamens and carpels) that are typically surrounded by a brightly coloured corolla (petals) and a green Calyx(sepals)
Sketch the basic anatomy of a flower
Briefly explain the functions of a flower
- attracts insects or pollinators that will transfer pollen from the anther to the stigma(pollination)
- ovary(base of the flower) contains seeds that will ripen into a fruit( angiosperms)
What is a fruit ?
A ripened ovary containing seeds
What are the functions of the fruit ?
- protect seeds
- aid in seed dispersal
- the flesh attracts animals to spread seeds
- seeds contain the embryo(developing plant) and endosperm(food for the embryo) in a seed coat(hard shell)
Explain the basic functions of the different parts of a flower
Sepals- support the flower
petals- attract pollinators
Stamen-male part of the plant( filament and anther) produces sperm-containing pollen
pistil/carpel -female part of the plant(stigma,style and ovary)
stigma-top part of the pistil where pollen sticks
style- support structure connects ovary and stigma
ovary- contains eggs, develops the fruit
What are the differences between complete and incomplete flowers and give an example of
Complete flowers- contain all four whorls(stamen,pistil, sepal and petals)
incomplete flowers- are missing one or more whorls, eg grass does not have sepals or petals
Explain the difference between perfect and imperfect flowers and give examples of each
Perfect flowers- have both male and female structures in the same flower, eg. Petunias
imperfect flowers only have stamens or pistils not both.
They can be separately located on the same plant ,eg. Corn or they can be located on separate male and female plants, eg. Asparagus
Explain how flowers are pollinated
-Is accomplish via animals, insects or wind
-Pollen sticks to the body of pollinators and is carried to the next flower
- plants pollinated by animals or insects are referred to as “showy” flowers, they are bright and beautiful, whereas flowers pollinated by wind are not “showy”
Explain why specific pollinators can be both good and bad to a species of plant
Good: because that species of angiosperms will have a source of self perpetuation
Bad: if the pollinator species decreases the plant could be at risk of extinction, eg. Fig trees and fig tree wasp species
Briefly explain the fertilisation of flowers
Is the union of egg and sperm. Double fertilisation occurs in angiosperms, one sperm fertilises the egg and the second combines with a cell in the ovary to form endosperm(food for the developing fertilised egg)
Briefly explain Spermatophyta(seed plants)
Primary means of reproduction and dispersal for most successful plants in earth. Seeds develop from female gametophyte and the tissue associated with it
Why are seeds reproductively superior to spores ?
1) spores= single cell
Seeds- multicellular well developed with embryonic roots,stem and leaves
2)seeds contain internal food supply= self sufficient
spores little food supply
3)seeds protected by resistant seed coat and can live for extended periods of time at reduced rates of metabolism till conditions are favourable
Spores no protective shell but can also live for prolonged periods of time at reduced metabolic rate till conditions become favourable to germinate
Name 3 similarities between gymnosperms and angiosperms
1) both contain vascular tissue xylem(conduction of water and dissolved minerals) and Phloem (conduction of food)
2) both have alterations of generations, diploid(sporophyte)and haploid(gametophyte). Gametophyte generation significantly reduced
3) both are Heterosporous, produce two types of spores, micro and mega spores
Briefly explain gymnosperms and give an example of
Name Adapted from greek meaning “naked seed”
Produces seeds that are totally exposed or borne on the scales of cones
Eg. Pine trees
Briefly explain angiosperms
Name derived from greek meaning “seed enclosed in vessel or case”
Produce their seeds within a fruit
Most successful plants
Reproduce via forming flowers, fruits and seeds
Sketch a flowering plants life cycle
Name the 5 main plant processes
Photosynthesis
Respiration
Photorespiration
Transportation
Translocation
Explain the process of photosynthesis
-Light energy from the sun is converted into chemical energy
-CO2 absorbed from atmosphere through the leaves, H2O from the soil through the roots.
- this produces Carb molecules containing large amounts of energy and O2 as a by product given back to the atmosphere
Where does photosynthesis take place in plants ?
In the chloroplasts.
Light energy absorbed by chief pigment Chlorophyll “A” ( drives processes of photosynthesis)
What are the internal factors that influence the rate of photosynthesis?
-Leaf structure and chlorophyll content
- decreased photosynthetic rate when carbs manufactured quicker than transferred from cell
- photosynthesis slows when their is a lack of water in the cells
What are the external factors that influence that rate of photosynthesis?
-Temperature
- light intensity
- quality and duration of light
- availability of carbon dioxide
- water supply
- mineral content of soil
Define the process of respiration in plants
- Defined as the oxidation of organic substances within the cells and the release of energy
Briefly explain the process of respiration in plants
Respiration is a chemical oxidation controlled and catalysed by enzymes(ATP&NADP) in the protoplasm that break down carbs and fats releasing energy to be used by the organism in doing work
What are some factors that influence respiration in plants ?
Water availability
Temperature
Availability of stored food
Amount of gaseous O2
Briefly explain the process of photorespiration in plants
Process of many higher plants where oxygen is absorbed and CO2 is expelled.
Reverse of photosynthesis
This process waste little energy and enhances nitrate assimilation( process where absorbed nitrate from the soil converted into protein)
Briefly explain the process of transpiration in plants
It is the loss of water from the plant or water vapour from the surface of the leaves
Water absorbed through the roots transported to the leaves via xylem, in the leaves small pores allow water to escape as vapour
Less than 5% of all water absorbed by plants remains for plant growth
What are the 4 functions of transpiration in plants ?
-Transport mineral irons
-Provides water to keep plants turgid to support the plant
- provide water for photosynthesis in leafs cells
- keep leaves cool by evaporation
Briefly explain translocation in plants ?
-Is the movement of food, water and minerals within a multicellular plant
-Water and dissolved minerals transported upward via Xylem from root to stems and leaves
- dissolved foodtransported up or down via Phloem
Xylem only up
Phloem many directions
What is the definition of plant succession?
Is the progressive development of vegetation in an area through a series of different plant communities, finally terminating in a climax community.
What is progressive succession ?
When successional change leads to veld improvement
What is retrogressive succession?
When successional change leads to deterioration of the plant community(disturbance such as over grazing, drought, fires, flooding)
Explain what is ment by primary succession
-Occurs where no vegetation has ever grown before, such as a rocky area.
-Lichens start to grow on rocks and when they die remains decompose forming humus which breaks down rock into soil
- soil habitat formed after many years allows for grass seeds to germinate and cover the area
- as grasses die of replenishing humus in soil new plant species such as shrubs and trees become established remaining for longer periods of time thus system stabilises
- grasses and lichens(pioneer species)
Trees and shrubs(climax species)
Explain what is ment by secondary succession
-Occurs in a area where vegetation was previously established
- if there is to much grazers in a area overgrazing of grass happens
- reducing grass bio mass and reproduction
- causing an increase in trees and shrubs growing causing shade further reduction in grass species success.
Leading to less grazing options(encroachment) and thus reducing grazers and over grazing
Name the 5 strategies for success of grasses
-Herbaceous stems and leaves
-Growing points at the bases of internodes and leaves
-plant architecture
- hybridisation, and asexually produced seeds
- leaf structure, photosynthetic pathway, climate adaptation
Explain herbaceous stems and leaves of grasses
- Most grasses are herbaceous.
- during favourable seasons they flourish completing their annual growth and reproduction while weather is warm and wet.
- during unfavourable seasons of cold and drought they die back, leaving their growing parts under or just at the surface of the soil.
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annual species survive unfavourable seasons as seeds
-perennial species survive dormant as rootstocks and rhizomes
In south africa annual species=dry western areas
perennial species=wetter eastern areas
Explain the growing points at the bases of internodes and leaves of grasses
- Most plants growing points at tips of stems and branches
With grasses 2 growing points : tip of each shoot and at the base of each internode and each leaf(most important) - when grasses get grazed or burnt they do not regenerate from the tips as other plants do meaning growth points seldom get removed allowing for continued development throughout the season
Explain plant architecture of grasses
-Leaves of grasses generally long, vertical and very thin, thus having an open canopy design allowing for maximum penetration of sunlight
- light reaches total area of leaf surface allowing for maximum photosynthetic efficiency
Explain photosynthetic pathways of grass
-There are two major forms of photosynthesis that occur in grasses C3 and C4 photosynthesis
- C3= occurs in leaf tissue with chloroplast evenly distributed( photosynthesise and produce starch simultaneously)
-C4= occurs in leaf tissue exhibits devision of labour(photosynthesises or produce starch separately)
Differentiate between C3 and C4 grasses
- C3 grasses lack rigidity due to loose cellular structure and function best at moderate temperatures, thus concentrated to northern hemisphere or high altitudes and moist habitats
- C4 grass species photosynthesise best at high temperatures and are most commonly found in the tropics or subtropics. Specialised starch producing cells lignify the plant making grasses stiff and stemmy
Explain hybridisation of grasses
Common in grasses
Leads to increase variability within population
Allows for grasses to take advantage of new habitats as they become available
Hybrids are nearly sterile due to chromosomes being present in multiples
This means hybrids do not need to sexually reproduce and offspring have exactly the right amount of chromosomes(asexual reproduction)
What are the differences between annual and perennial grasses ?
